How do ocean sediments capture information about atmospheric carbon dioxide levels?

Ocean sediments serve as a historical archive of atmospheric carbon dioxide levels primarily through the preservation of organic materials. When organisms such as phytoplankton and other marine life die, their remains accumulate on the ocean floor. These organic materials can contain carbon, which reflects the atmospheric CO2 levels from the time these organisms were alive.

By conducting isotopic analysis on the carbon found in these sediments, scientists can determine the ratios of different carbon isotopes, such as carbon-12 and carbon-13. Variations in these isotopic ratios can provide insights into past carbon cycles, including fluctuations in atmospheric carbon dioxide levels.

This ability to preserve historical CO2 levels over thousands of years allows researchers to reconstruct past climates and understand how carbon dioxide has influenced global temperatures and climate change over time.